Great Springs Trail Race - Natural Bridge Caverns
Race: 4 miles, 8 miles, 16 miles, Last Person Standing Run, Last Person Standing Ruck, Youth 1 Mile
When: September 20, 2025 til The Last Person’s Standing
Where: Natural Bridge Caverns
26495 Natural Bridge Caverns Rd, San Antonio, TX 78266
Closest cities: San Antonio, New Braunfels, San Marcos
Closest bigger cities: Austin, San Antonio
Join us for our most unique race ever! Starting in the Natural Bridge Caverns, which is part of the Comal Caverns network, this race kicks off with breathtaking views of the world below our feet as the start line is in the depths of the Natural Bridge Caverns. Once you emerge to the sunshine of a beautiful day, you’ll wind your way through beautiful trails over flowing hills and through wooded sections. You can choose from 4 to 16 miles distance or go big with the Last Person standing format.
What Is Last Person Standing?
It’s the ultimate showdown of endurance and mental grit. In this Last Person Standing event, runners take on a 4.1667-mile loop and ruckers face a 2.3-mile loop—every hour, on the hour. Finish your loop in under 60 minutes, and you earn the right to start the next one. Pick up the pace for a lap and you can even get a few minutes to refuel, use the toilet or even sleep before the next lap starts on the hour.
Miss the cutoff? You're out. Don’t make it back to the start line at the hour? You’re out.
The race doesn’t end until there's just one person left standing who can finish the loop in 1 hour. No finish line, no mercy—just loop after loop, testing how far you're willing to go when the only thing standing between you and the win… is everyone else.
And at the heart of it all? A race hub that turns into an all-day and all-night party—cowbells, cheers, music, and madness that gets louder and more electric every hour as the field thins and the stakes rise.
Besides the beautiful trails we will get to use for the race, Natural Bridge Caverns is a place for stunning underground caverns and fun above-ground adventures!
You can run the 4 mile, 8 mile or 16 mile race and then tour the caverns with your supporters. If you want to take to the skies, you can soar on the 60-foot-high Twisted Trails Zip Rails & Ropes Course! Theses activities will be open during their regular business hours.
When you register for the race you will receive a discount code for 10% off the Discovery Tour, Hidden Wonders Tour, Twisted Trails, and the AMazeN Ranch Round Up.
Natural Bridges Caverns will also have their restaurant and snack stands open for a hearty meal after your adventure. Or you can get a hamburger for the few minutes you have between laps in the Last Person Standing race.
We are also extremely thankful to be aligned with the amazing Great Springs Project for this race. Not familiar with it yet? Check out the link below or come to the race to learn how the Edwards Aquifer beneath these trails is crucial for providing sustainable clean water to our growing cities. We are incredibly proud to support their impressive efforts through this trail race!
Race Schedule
EVERYTHING HAPPENS AT THE RACE SITE
WEDNESDAY, THURSDAY AND FRIDAY
Course Marking and Race Hub Setup: Sun up to sun down pretty much.
SATURDAY
Packet Pickup:
6:00am-8:30am (for all distances)
9:30-10:00am (for Youth Races)
Start:
Last Person Standing Start
7:00am: Last Person Standing Run & Ruck Mass Start
4 miler, 8 miler and 16 miler Start
7:45am: First group start
8:45am: Last group start
Youth 1 Mile
10:30am
Final Lap Cutoff: 11:30am (16 milers must be on your last lap)
Final Cutoff 4 mile, 8 mile and 16 mile: 1:30pm (course open to Last Person Standing only)
Course Information
RACE DISTANCES: 4 mile, 8 mile, 16 mile, Last Person Standing
ROUTE DETAILS:
The race will start in the caverns. Last Person Standing will all start at the same time. For the 4 mile, 8 mile, 16 mile and Youth 1 mile racers, you will be assigned to a starting group based on your check-in time at packet pickup. For this race, awards will be based on chip time, rather than the usual gun time.
The course will utilize a core 4.1667 mile loop for the Last Person Standing run and a 2.3 mile section for the ruck.
For the last person standing the Race Director will blow a whistle 3 times at 10 minutes to the hour and then 2 times at 5 minutes and then 1 time for the start of the next lap.
Course Map Coming Soon
Course Markings
We go above and beyond on our course markings, and have become known around the world for it. We will have Tejas Trails barricade tape blocking off any open intersections; yellow arrows stapled to stakes, signposts, fences, and trees; and hundreds of confidence markers between. You never have to navigate or use a map.
Course markings are not color-coded per distance. When you get to an intersection where a shorter distance breaks off from the longer main loop, there will be signs with distances on them pointing the appropriate ways. Simply follow the signs with your distance on them. If you don’t see your distance just beyond that intersection, you just missed your turn. Don’t ever cross barricade tape. It usually is required that we keep the tape on the ground, but it’s always obvious, and will act as a guardrail for you at open intersections.
Now of course, you can get off course… So if you’re new to trail running, you have to train your brain to keep looking up; and especially don’t trust the person in front of you. We have a special “Lemming Award” for those who blindly follow someone else off course and then get mad at us.
Aid Stations
We will provide a lot of aid station support for you.
There will be 1 full aid station at the finish/next loop arch. This aid station will be fully stocked with fruit, sandwiches, water, Tailwind and various sweet and salty snacks during the day. At night we will fire up the cookers to provide hot foods such as ramen, broth, quesadillas and bacon.
There will also be a water and ice station on the course.
We will have cold sodas and water waiting for you at the finish line.
We are a cupless race series, meaning we do not provide cups at the aid stations. Please make sure you have a water-carrying bottle, belt, or vest, plus an extra packable cup or something to get extra drinks at aid stations. We usually have these for sell at packet pickup or our merch tent onsite if you forget to bring one.
Race Day Results & Timing & Scoring
Start Options
There will be a mass start for the Last Person Standing Run and Ruck. The 4 mile, 8 mile and 16 mile races will start in groups in the cavern based on check-in time at packet pickup.
Results and Live Split Updates
Click this button on race day to see updated results each time a runner passes a timing mat on the course and the final results. Timing mats are always at the start/finish/next lap line, and sometimes an additional mat is placed out on the course.
Timing and Scoring
The results page will show two times for each runner. “Gun Time” and “Chip Time”. Here’s what that means for you:
“Gun Time” is the time from the mass start (when the starter officially starts your distance) until when you cross the finish line.
“Chip Time” is the time from when you actually cross the start line until the time you cross the finish line. This will be official times for award rankings for the 4 mile, 8 mile and 16 mile races.
Drop Bags
We are not offering drop bag services for this course. Please do not leave any personal bags or belongings on the course.
4 mile, 8 mile and 16 mile Runners:
You are welcome to leave a drop bag and ice chest anywhere around the race hub, other than around the packet pickup tent or in the race chute, for when you come through each lap and are done.
Last Person Standing Runners:
We will have plenty of space for drop bags and crew support stations at the race hub for the Last Person Standing runners. There will be signage there when you arrive to indicate where you can setup your drop bag station. Canopies of 10’ x 10’ or less are allowed but must be properly staked down in case of high winds.
Ruck Division
If you haven’t experienced a ruck challenge or competition, they are wonderfully simplistic and can take place in a variety of looks and feels. We are not going to have challenges along the way. Just straight hiking/jogging on a trail with a ruck (pack), from the start line to the finish line. So, all you need to join in on the Ruck division is a ruck (pack) with some weight in it, and the ability to cover the miles.
Top finishers will be rewarded nicely (same divisions as our regular trail runs). All finishers will receive a patch and finisher medal.
We are now offering a ‘long course’ and ‘less long course’ at each event we offer the Ruck Division!
FURTHER DETAILS:
If you weigh under 150lbs, we will require a 20lb weight.
If you weigh over 150lbs, we will require a 30lb weight.
Mandatory ruck weigh in will take place prior to the start when you pick up your timing chip, and at the finish line.
Weight cannot be anything consumable or wearable like food or water or clothing. But pretty much anything else goes.
The mandatory amount of weight cannot be on the shoulders or chest. It must be on your back.
No sling bags or duffel bags or anything like that.
Any type of backpack (ruck) is acceptable otherwise.
No trekking poles allowed.
You can carry additional gear and supplies like food, water and clothing (and you should), but that will be additional weight.
Volunteering
We fully recognize we could not (and would not want to) put on any of these events without your help. Volunteers breathe life into these events. You make them personal for people. We no doubt need you and love this component to our business. So, know that we will always do everything we can afford to do to help you enjoy your time out there in the trenches helping those runners achieve their goals and dreams.
As a volunteer, you get:
Park entry fees
Food brought to you while you are volunteering
Shirt, hat, race swag, etc.
Loads of good memories
All the gear and supplies you need to successfully accomplish your task
Volunteer hours exchanged for future race entries
We can always use help, specifically for: course marking, packet pickup, aid stations, finish line, course sweeping, teardown, and more!
Swag & Stuff
Your race entry comes with a bunch of good stuff! You’ll get the comfort of our world-renowned course markings so you don’t have to worry about getting lost. You’ll get our notorious staff and volunteer support (and probably leave with new friends you met at an aid station or the finish line)! We will offer a plethora of aid station food and drink options, as well as finish line drinks. There will be a relaxing race hub area with backyard games and toys for kids to play with for your spectators, friends, and family.
You can also expect awesome gear you’ll actually want to wear, and a truly unique medal that you’ll be proud to have. Those who sign up before the shirt cutoff (when we actually have to put the shirt order in) will receive a nice shirt. Sometimes long sleeve, short sleeve, sleeveless, tank top, or something else we find that’s cool and different from the year before. Those who register after that date will receive a cool non-size specific item, such as a hat, beanie, arm warmers, scarf, drink ware, or something else we find.
If you don’t like the swag item you received, you may swap your item after the final Packet Pickup is over (when we have ensured everyone got the item they signed up for). You can also purchase the other item(s) if you like all of them. This will all happen from the Tejas Trails merchandise tent when it’s onsite, and otherwise will be made available at the Packet Pickup Tent or the Finish Line Tent.
Please note, we don’t always get the shirt color we had planned these days, as things are goofy with shipping and fulfilling. If the shirt color changes, sometimes we have to change the design colors too. But you can count on a quality item.
Timing & DNF
Chip Timing
All races will be chip timed. Chips will be attached to an ankle strap, picked up on RACE MORNING ONLY at the event venue, and must be worn on your ankle during the race. Chips are likely to not work if worn anywhere other than your ankle.
Once you finish, we will have a bin for you to place your chip into. Our head timer will take care of it from there.
Please reference the “Start Options” section above for exact details of how we are utilizing “Gun Time” vs “Chip Time”.
Check Out
If you leave the race for any reason before completing the full race distance, you must turn in your timing chip. If we have your Chip, then we know you have left the course & we won't go looking for you all day & night.
DNF (Did Not Finish)
For 4 mile, 8 mile and 16 mile runners, if you decide to not finish the distance you registered for, you may get a finisher medal to commemorate the miles you did finish if you completed a shorter race distance; but you will be a DNF in the results. You will not be in contention for awards for the shorter distance category.
Split Time Collection
Some races may have mid-point reads to help us track progress during the race. If you see a timing mat on the course, make sure you run over it.
Pacers
Pacers are not allowed for this event.
Overall Awards
We love celebrating our top finishers! However, we don’t have awards ceremonies at most of our events. But all the top finishers will receive some really great stuff!
We will have some fun, special, handmade overall awards to hand out when you cross the finish line. Volunteers will check results as you cross, but sometimes there’s a delay since our events are mostly remote. So, if you think you may be in contention for one, please ask before leaving.
Please note, we do not mail awards to anyone who leaves without their earned award. If there is any signal, you can also look up how you did on the results page (found in the pre-race email and at the top of this event webpage).
For this race, we award the Top 3 Overall by gender + Top 1 Masters by gender (50 & Older).
There are special awards handed out uniquely for the Tejas 250, Tejas 300, and Tejas 400. And yes, the Last Person Standing race mileage does count for Tejas 400 if you complete more than 12 rucking laps or 7 running laps.
For anyone who completes 500, 1000, 1500km or miles at the same event, we give away special fleeces for you to make others jealous with.
Families & Youth Run
Tejas Trails is for families! We have a few things going on to help everyone have fun on race weekend.
For you runners who are trying to figure out how to train and race while trying to be a good friend, partner, spouse, or grandparent.
For you family members and friends who are trying to support your runner, but get bored out of your minds trying to keep your young ones safe and busy.
Our goal is for the runner’s family and friends to have fun things to do, enjoy hanging out, exercise, play in the woods, and create great life-long memories together. Bottom line, we want families to grow closer together because of Tejas Trails events. So, we will provide things like family discounts, yard games, youth races, and a family-friendly environment.
Getting Here
Everything happens at Natural Bridges Caverns. (Google Maps Link)
Parking
Parking is the same for runners and spectators. There will be a couple different places the park will put in upon your arrival. Just follow their guidance and signage. No parking along the edge of the road is allowed. You will be parking somewhere between 200 yards and 600 yards away, so plan accordingly. If you are coming with a friend or family member, they can drop you off very close and then go get parked.
Camping & Lodging
There is no camping at this event, but the good news is that the park is close to several major cities, which has more than ample options for camping, BnBs, and hotels.
